STEEP323 computes spectral effective emissivities and radiance temperatures for an axisymmetric cavity formed by rotation of a non-self-intersecting polygonal line around an axis. STEEP323 is the most powerful blackbody emissivity modeling program to date. It employs the 3C BRDF model, which allows to reproduce adequately optical characteristics for the absolute majority of materials used in desing of blackbody  radiators operating from UV to Far IR. Program contains the innovative algorithms for fitting parameters of the 3C model to measured in-plane BRDFs and for  splitting spectral reflectance onto components of the 3C model. If experimental data are insufficient, STEEP323 allows to build a priori 3C BRDF model and perform parametric study. For details, see STEEP323 Key Features list, Comparative Table, or download the Manual.

Download STEEP323 Evaluation Version (11.3 MB)

Download STEEP323 Manual (7.6 MB)

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STEEP323 Key Features
STEEP323 is based on the proprietary algorithm of the Monte Carlo ray tracing method (MCRT) implemented for axially symmetric cavities formed by rotation of polygonal line around the axis and adapted for the 3C BRDF model. See "Applied Optics" article for which numerical examples were prepared with the help of STEEP323.

STEEP323 has the unique utility that uses the particle swarm optimization technique for multidimensional global optimization applied to the fitting of the 3C model parameters to the measured in-plane BRDFs. Besides, STEEP323 allows to extend the applicabilty of the BRDF parameters fitted for one wavelength to the spectral range in which blackbody radiation characteristics should be computed. The use of experimental data for materials and coatings of the internal surface of a blackbody radiating cavity provides the highest reliability for results of numerical modeling.
STEEP323 doesn't require special efforts for installation. Download the Evaluation Version, unzip it, save STEEP323 folder in the convenient place on the hard drive and run STEEP323.exe. The Evaluation Version has several restrictions (see details in the appropriate Section of the Manual.) After purchasing the product license, you'll receive the activation key which will turn the Evaluation Version into the full-functioned unrestricted program. The Software Licence Agreement is included into the Manual. Go to the Purchase page to see how to buy the license.

Although STEEP323 is simple to use and has user-friendly interface, such sophisticated tasks like building the 3C BRDF model and interpreting the results of Monte Carlo modeling may require special knowledge and experience. Therefore, Virial International recommends to purchase STEEP323 together with the technical support subscription: subscribers can rely on the one-year unlimited support from Virial International in resolving the most complicated computational problems of blackbody radiometry and assistance in the results interpretation.
Modeling of axially symmetrical cavities formed by revolving of a polygonal line having up to 1000 segments (1001 vertices)
Successive (wavelength-by-wavelength) calculation of effective emissivities and radiance temperatures for up to 501 wavelengths
Possibility to build 3C BRDF model from scratch or to fit its parameter to in-plane BRDFs measured at up to 6 incidence angles for one wavelength
Possibility to separate the spectral directional-hemispherical reflectance measured at one incidence angle into the components of 3C reflection model to make it wavelength-dependent
Calculation of effective emissivities and radiance temperatures for up to 6 axisymmetric temperature distributions simultaneously (at one run, using the same set of ray trajectories)
Defining of up to 1001 temperature points in each temperature distribution
Four types of viewing conditions (Normal, Directional, Conical for divergent and convergent viewing beams, Integrated )
Successive calculations for up to 201 viewing conditions of the same type
Possibility to take into account the contribution of a background radiation
Built-in expandable databases for:
· Geometrical parameters, reflection models for materials, temperature distributions, and viewing conditions for blackbody radiators
· Measured BRDFs and spectral dirrectional-hemispherical reflectances, results of BRDF fitting and spectral reflectance splitting
· Wavelength-dependent 3C BRDF models of materials and coatings
· Computed spectral effective emissivities and radiance temperatures
Interpolation of spectral data stored in the database on the prescribed wavelength set
Automatically generated and stored in the RESULTS database calculation reports in ASCII format
Editable, exportable, and  printable 2D graphs representing:
· Scaled cross-section of cavity generatrix
· Viewing conditions
· Measured and fitted BRDFs; measured SDHRs and results of their spectral splitting
· Dependence of material’s SPRs on wavelength
· Temperature distributions along cavity generatrix
· Dependences of effective emissivities on the wavelength
· Dependences of effective emissivities on one variable parameter of viewing conditions
Possibility to save 2D graph data in text file or as MS Excel spreadsheet
3D interactive and editable plots of 3C BRDF models in spherical coordinate system
Possibility to save 3D graph data in text file
Possibility to save in file or copy to clipboard 2D and 3D graphs as bitmap
Minimal equirements to hardware and software:
· CPU frequency 2 GHz
· Screen resolution 1600 ×1024
· RAM 3 GB
· Hard disk space 25 MB
· Video card 1 GB video RAM; OpenGL 2 compatible
· OS MS Windows® XP (with SP3), 7, 8 (in compatibility mode)